Multilayer high-pressure vessels manufactured by way of helical winding of a steel strip onto a central pipe in such a manner that every subsequent layer is placed in the direction opposite to that of the preceding one have no fastening welding seams or have only partial fastening in some outer layers of the steel strip. As a result, the strength of the high-pressure vessels depends on tightness of adherence of the strip layers to one another and accuracy of the steel strip winding. The tightness of adherence of the steel strip layers to one another and the accuracy of the steel strip winding depend, in their turn, on the value of tensioning of the steel strip being wound and the accuracy of adjustment of the angle of feeding of the steel strip to be wound. The rolled steel strip is inevitably crescent-shaped and has deviations in its width. Said deviations require an additional adjustment of the present angle of the steel strip winding in the course of winding. Therefore, rigidity and stability of the systems used for winding the steel strip, as well as an accurate adjustment and a fast correction of the parameters of the steel strip winding depending on current deviations in the shape of the steel strip are of a paramount importance during manufacture of bodies of multilayer high-pressure vessels.
Widely known is a plant for manufacturing helical seam pipes made of two strips (FRG Pat. No. 1222456; Class 7b, 37/12, published in 1962), which comprises a shaping unit bending the steel strip into a spiral and two technological lines for preparation of the steel strip, located at the opposite sides in relation to the pipe axis. Each technological line for preparation of the steel strip comprises a decoiler, drive rollers feeding the steel strip to the pipe, a straightening machine, an arrangement for cutting the steel strip, a fixture for butt welding of the ends of the steel strip and guide rollers, all arranged in succession along the direction of movement of the steel strip, all this equipment being mounted on a common frame installed on railways and capable of turning in the horizontal plane to change the angle of feeding of the steel strip during the winding thereof.
The afore-said device is characterized by a low accuracy of setting and adjustment of the angle of feeding of the steel strip because the process of setting and adjustment of the feeding angle of the steel strip necessitates a turn of the whole technological line for preparation of the steel strip, which is of a great weight and large dimensions. The plant under description used for manufacturing helical seam pipes occupies a considerable production area as the technological lines for preparation of the steel strip are located at the opposite sides of the pipe axis.
Also widely known is a mill for manufacturing bodies of multilayer high-pressure vessels (U.S. Pat. No. 2,600,630; Class 29-446, published in 1952), comprising rotators of the body of the high-pressure vessel, which have the butt end portions of the high-pressure vessel secured therein, and a technological line for preparation of the steel strip for its winding onto the vessel central pipe, the steel strip coming from a coil. The technological line for preparation of the steel strip comprises a decoiler, straightening rolls and guide rollers, all arranged in succession down the direction of movement of the steel strip. The technological line for preparation of the steel strip is mounted on a frame installed on a carriage moving along railways, the railways being positioned parallel to the high-pressure vessel body being wound at one side thereof, the movement of the carriage being mechanically matched to the rotation of the high-pressure vessel body. The frame mounting the technological line for preparation of the steel strip is made capable of turning in the horizontal plane to feed the strip to the vessel at a winding angle.
The mill also comprises an arrangement for tensioning the steel strip, which is mounted, relative to the axis of the vessel body, at an angle corresponding to the angle of winding of the steel strip and is movable along the high-pressure vessel body. The fixture for welding the steel strip to the end portions of the vessel body and turns of the steel strip to one another can also move relative to the vessel body.
The above-mentioned mill for manufacturing bodies of multilayer high-pressure vessels does not provide for a sufficient tightness and accuracy of winding of the steel strip because, when setting and adjusting the angle of winding of the steel strip, all the equipment of the technological line for preparation of the steel strip has to be turned around, this being still worse in case the layer of the steel strip is wound several times and in opposite directions. The fact that the carriage carrying the equipment of the technological line for preparation of the steel strip is mounted at one side of the high-pressure vessel body reduces rigidity and stability of the mechanical system of the mill during winding up of the body of a vessel of a big diameter when the tension of the steel strip is great. In the case of winding up of the bodies of vessels of great dimensions and weight the mechanical matching between the movement of the technological line for preparation of the steel strip along the high-pressure vessel body and the rotation of the body of the high-pressure vessel does not provide for an accurate winding of the steel strip owing to a low rigidity of the mechanical system of the mill being described. When changing the direction of winding of the steel strip, the equipment of the technological line for preparation of the steel strip has to be put at the other side, which results in wasted work time. Besides, every time a new layer is to be wound the end of the steel strip is chamfered at an angle which is a mirror reflection of the angle of winding of the previous layer, which brings about an excessive consumption of metal.